Covalent Bonds and Formulas. Advanced Periodic Table. Www.johnrouda.com/google/apps/elements/ Periodic Table of Videos. Atomic and ionic radius. You can see that as the number of protons in the nucleus of the ion increases, the electrons get pulled in more closely to the nucleus. The radii of the isoelectronic ions therefore fall across this series. The relative sizes of ions and atoms You probably won't have noticed, but nowhere in what you have read so far has there been any need to talk about the relative sizes of the ions and the atoms they have come from. Neither (as far as I can tell from the syllabuses) do any of the current UK-based exams for 16 - 18 year olds ask for this specifically in their syllabuses. However, it is very common to find statements about the relative sizes of ions and atoms. I am fairly convinced that these statements are faulty, and I would like to attack the problem head-on rather than just ignoring it.
Important! For 10 years, until I rewrote this ionic radius section in August 2010, I included what is in the box below. Choosing the right atomic radius to compare with Group 7 Group 6 Group 5 Conclusion.